Relax the test more since hash of Symbols might change between versions

Author: YingboMa

src/systems/abstractsystem.jl

@@ -737,7 +737,7 @@ function n_extra_equations(sys::AbstractSystem)
     nextras = n_outer_stream_variables + length(ceqs)
 end
 
-function Base.show(io::IO, ::MIME"text/plain", sys::AbstractSystem)
+function Base.show(io::IO, mime::MIME"text/plain", sys::AbstractSystem)
     eqs = equations(sys)
     vars = states(sys); nvars = length(vars)
     if eqs isa AbstractArray
@@ -806,7 +806,7 @@ function Base.show(io::IO, ::MIME"text/plain", sys::AbstractSystem)
         state = get_tearing_state(sys)
         if state !== nothing
             Base.printstyled(io, "\nIncidence matrix:"; color=:magenta)
-            show(io, incidence_matrix(state.structure.graph, Num(Sym{Real}(:×))))
+            show(io, mime, incidence_matrix(state.structure.graph, Num(Sym{Real}(:×))))
         end
     end
     return nothing

test/state_selection.jl

@@ -1,4 +1,4 @@
-using ModelingToolkit, OrdinaryDiffEq
+using ModelingToolkit, OrdinaryDiffEq, Test
 
 @variables t
 sts = @variables x1(t) x2(t) x3(t) x4(t)
@@ -21,7 +21,7 @@ let dd = dummy_derivative(sys)
     end
     @test has_dx1 ⊻ has_dx2 # only one of x1 and x2 can be a dummy derivative
     @test length(states(dd)) == length(equations(dd)) == 9
-    @test length(states(structural_simplify(dd))) <= 6
+    @test length(states(structural_simplify(dd))) < 9
 end
 
 let pss = partial_state_selection(sys)